A character recognition technique is generally designed to specify the position of a character row (character string) segmentation and then to specify the segmentation position between characters in the character row (character string) whose position is determined (patent reference 1, for example).
FIG. 12 is a flowchart showing a process flow of a conventional character segmentation. In the character segmentation process (Step ST1 through ST3), a horizontal projection histogram is first calculated on a character line (character string). In this projection calculation, pixels in the vertical direction are added (or the arithmetic mean is calculated); the adding range is set in the range which has the top and bottom edges of the character line (character string) obtained by the character line (character string) segmentation unit, as its end points. With respect to the projection profile obtained in this way, the level value of the projection profile is compared with a predetermined threshold value slev (the method for setting a slev may adopt the method disclosed in patent reference 1), to judge the period exceeding the threshold slev as a space between characters. The boundary position is set at a midpoint between the both end points of the space.